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5 Series DIY Knowledge Is Power! ~ The place for do-it-yourself threads on a variety of topics. Start a thread describing a particular job (oil change, cooling system overhaul, brakes, shocks and springs, etc.) or search for one you need help with!

Thanks to Elvis and all the others who have contributed to this thread. I thought I would just add my experience, particularly for UK car owners.

I have a 2002 530D and last week the blower suddenly stopped working. All the functions on the climate control appeared to work - I could hear clicking noises when switching the air con on - there was just no air blowing in the car.

My blower was working properly until it stopped - I didn't get any of the intermittent problems or partial operations others talk about.

First I checked fuse 76 which on UK (all?) cars is above the back of the glovebox. If you lie on your back with your head under the glovebox and look to the left rear corner of the glovebox as you are viewing it (i.e. nearest the front of the car and nearest the transmission tunnel) there are a couple of fairly chunky wires that terminate in two (bigger than normal) fuse holders. You cannot tell they are fuse holders as you cannot see the fuses because you are looking at the back of the fuse holder where the wires enter. To remove the fuse you need to get your hand above the terminal, feel for the middle of the fuse and pull it vertically upwards (toward the roof). The chunkiest wire is for the auxiliary fan (fuse 75) and has a 50 amp fuse. The other one (fuse 76) is the blower fuse (40 amps). My blower fuse was fine so I proceeded to the next stage.

The next logical stage to check is the FSU. Variously known as the Final Stage Unit, Final Stage Resistor, Limit Switch (in the UK Haynes manual), hedgehog, porcupine, etc.

You have to remove the carpet piece on the transmission tunnel (1 phillips screw to the right and then slide the whole panel to the rear of the car) and the plastic trim piece that covers the pedals (three phillips screws then I waggled the piece over the two star/torx screws with rubber washers - you could also remove them if you have the tool to hand).

I got the part out in about 10 minutes from starting, plugged in the new FSU and hey presto the blower (and therefore air con) is back! Another 10 minutes and the trim is back in place, job done.

One thing I now notice (it may have been there before but I never noticed) is as soon as the ignition is switched on I get a weird noise for half a second like an aeroplane's engines shutting down (i.e. the pitch drops) before the (different) sound of the blower fan picks up speed. The first noise only lasts for half a second or so and then disappears. Anyone else get this as normal?

The last points to note are that the FSU that I replaced is identical on the outside to the new one (i.e. black plastic body with parallel heatsink spines rather than the aluminium body with the tapered spines - the "old" one in Elvis's photos). This means that it was either replaced already or by 2002 in the UK they had changed the design. It doesn't have the current BMW part number so it may be an interim design. Finally the (after market) part I got is marked as made in Germany and the company name on the box and the part is Meyle

I hope this post helps someone else like the previous entries helped me.

Thanks to Elvis530i for this helpful post. I just replaced mine today and it turned out to tougher than I expected. The plug was sticking and really not budging. After 15 minutes of wrestling with it, I sprayed some WD-40 into the clips holding the plug to the FSU and voila, it just popped right out!

Hi! Sorry to bring this up again; but, I'm not getting any responses in the forum, so I'm trying this method. As you can see, I'm at a loss. Any help would be greatly appreciated. THX...Matt

Quote:
Originally Posted by MisterMatt
I've been working on my blower fan combo & have removed the FSU; however, prior to buying another, I would like to test the blower motor. I saw your pin-out on another forum msg. and it looked like if I tapped at pin 2 for 12v, then to pin 1, then pin 5, thru test lamp, to ground, the fan should run. The lamp lights, but no fan runny. Anyone have any suggestions? I'll try to include a link to where I found the schematic that I think you posted...

I agree! Sorry I didn't chime in sooner. My FSU seemed to have "fixed" itself (except for the early morning wheezing) so I didn't pursue this further.

But I did send your BMW FSU wiring diagram to an electrical engineer friend in the silicon valley who wrote back the following that might help the next DIY.

> Does this electrical BMW FSU thingey look easy to debug?

Well, if you have access to the wires in the car, I guess it shouldn't be too bad.
You can see that the terminals are:
1,5) blower
2) +12
3) control input (in spite of being drawn as the collector of a bipolar transistor!)
4) ground

So I would:
A) spray WD40 on the contacts
B) check terminal 2 for voltage
C) put a two channel scope on terminals 3 and 1, and then 3 and 5

Now the question is, is that much effort worth more than
the $100 or so to just replace the unit? Consider your
options. Either the unit is bad, so replacing it is required.
Or, the control unit is bad. That's going to cost a bundle.
So maybe spending $100 is a reasonable thing to do.

To Bluebee;

I think that I'm doing these posts all wrong, but I'm trying again. I just wanted to send a reply to this msg to Bluebee, not the world, but I guess I don't know how to do that. OH well...

Hi! Sorry to mail you directly; but, I'm not getting any responses in the forum, so I'm trying this method. As you can see, I'm at a loss. Any help would be greatly appreciated. THX...Matt

Quote:
Originally Posted by MisterMatt
I've been working on my blower fan combo & have removed the FSU; however, prior to buying another, I would like to test the blower motor. I saw a pin-out on another forum msg. and it looked like if I tapped at pin 2 for 12v, then to pin 1, then pin 5, thru test lamp, to ground, the fan should run. The lamp lights, but no fan runny. Anyone have any suggestions? I'll try to include a link to where I found the schematic...

Thanks for posting the how-to on replacing this unit. Not a hard thing to do...even for me! I was bound and determined, had a hard time taking out the plug so monster hands husband wrestled it out for me. I did the rest, put back all the parts, bolster and glove box cover. For those still thinking about DYI, go ahead! I'm a girl, and I did it! LOL

I have the part on order and it should arrive tomorrow.
I could not wait so I went ahead and removed the existing FSU.It was a struggle to get the plug out of the FSU. Can I operate the car with the FSU out ? , or do I have to wait till the new one is in ? I do not know if the break in the circuit is important for any other systems.

hi elvis many thanks and 2 all members 4 contributions thanks, again your posts helped another poor beema owner lol. i only have 1 thing 2 add that is if u in uk plz remember most ov posts r off leftys so make sure u read properly b4 u start or itll tek u longer 2 put bak wot u stripped than fit the part .lol my fault but very plzd with help thanks again kev

hi every1 many thanks 4 all expertise (elvis 530i), managed 2 get resistor from local motorist discount(a friend luckily) for £48 so shop around as bmw quoted me 66 + vat and 70 + vat dont no y
but job done, took a little longer 2 do on uk rhd but still only 40mins. ended up an inexpensive fix 2 something bmw could not suggest unless u took it in (god knows wot that costs)
i am a very satisfide beemer own just need a little help now and again so big2 all that take the time 2 post, thanks again kelone30

My situation is slightly different, so I'm hoping someone can offer some advice.

My blower works fine, to a certain extent. I don't have the battery draining problem nor intermittent function and the controls work just fine.

My symptoms are simply that the blower sounds like it is pulsing. If I turn it the fan speed up to maximum, its fine but when I drop the speed, it starts pulsing again.

Sometime, it will be pulsing at low speeds, I turn it up full for a few minutes and then when I turn it back down again, it doesn't pulse, but next time I get in the car, same thing happens again.

Has anyone else had just this problem and found the replacing the FSU solved it ? I have a funny issue its an issue with the motor. Bad news of course is that they are very expensive and rather hard to get at in order to make a replacement.

My situation is slightly different, so I'm hoping someone can offer some advice.

My blower works fine, to a certain extent. I don't have the battery draining problem nor intermittent function and the controls work just fine.

My symptoms are simply that the blower sounds like it is pulsing. If I turn it the fan speed up to maximum, its fine but when I drop the speed, it starts pulsing again.

Sometime, it will be pulsing at low speeds, I turn it up full for a few minutes and then when I turn it back down again, it doesn't pulse, but next time I get in the car, same thing happens again.

Has anyone else had just this problem and found the replacing the FSU solved it ? I have a funny issue its an issue with the motor. Bad news of course is that they are very expensive and rather hard to get at in order to make a replacement.

Any help would be greatly appreciated.

I have not heard of that symptom before, sorry. It might be the FSU, but I'm just speculating here.

Another happy customer! For the longest time I was wondering why my car sounded like Darth Vader with the engine and power off, and why i was burning through batteries every 1-2 years and/or battery would be dead if I left the car untended for several days. Then in the past week battery died and the blower stopped working completely. Local dealer wanted $130 for the FSU, with advice gained here, purchased through Autohausaz for half as much. With the expert detailed DIY article, 2 Heinekens and 15 minutes later, problem fixed and now working like a charm. Thank you!

Im from Australia and i just orderd the part from america on ebay cost me AU$95 incl shipping. Adelaide BMW wanted $2000 to fix the problem, i decided i would find a cheaper way and looks like i have! I have a 318i 2004 and I am going to try and change this part next week, any suggestions on the differences on changing it on the right hand drive models??

After a couple of years of replacing the car battery and resisting "professional" advice to have the dashboard removed to have this issue attended.I have solved my problem thanks to this post.
I have saved between 3 and 5 hundred pounds,based on the estimates I recieved.

I have a 2002 BMW 525i and a couple of weeks ago the AC/Heater fan started to run uncontrollably. When I manually shut off the fan, it ran at even a higher speed. It even ran when the engine was off and the key was removed from the ignition. It would come on in the middle of the night and cause the battery to completely drain. I read your posting and followed your instructions and now the problem is solved! I replaced the blower motor resistor (final stage unit), which I purchased from Autohaus in Arizona for $73.00. The part was a lot cheaper here than at the dealer (which I would never go) or a local auto parts store. Thanks! You saved me time and money.